[Long-Chain Free Fatty Acids Influence Lipid Accumulation, Lysosome Activation and Glycolytic Shift in Various Cells In Vitro].

Hydrophobic molecules may be toxic when present in excess. When dissolved in membranes, hydrophobic molecules disrupt membrane function. Studies on the effects of free fatty acids (FFA) on cultured cells contradict each other. Here we describe the effects of FFA on various human cells in culture. The addition of long-chain FFA (oleic, palmitic, linoleic, linolenic, etc.) to cultured cells led to lipid accumulation in hepatocytes and muscle cells, initiation of autophagy, and uncoupling of oxidative phosphorylation. Although treated cells increase their oxygen consumption, metabolic shifts in favor of glycolysis were observed. All these effects were expressed to varying degrees in different cells and with the addition of different FFAs. The mechanisms of these FFA effects are discussed, as well their practical implications.

[Healthy Aging: Antioxidants, Uncouplers and/or Telomerase?]

The free radical theory of aging was proposed in 1956. Although it does not fully describe the mechanisms of aging, it is generally accepted that reactive oxygen species (ROS) are one of the pathogenetic factors in aging and, in particular, in the development of pathologies associated with aging. The main source of ROS in the cell is mitochondria. Antioxidants directed to mitochondria have a positive effect, but have low efficiency. The problem is that increased amounts of antioxidants disrupt normal cellular redox reactions, and a low amount of antioxidants is not able to seriously affect the processes. Protection against ROS may be more effective if the rate of ROS formation is reduced. There is a natural mitochondrial uncoupling process that significantly reduces ROS production. The weak uncoupler dinitrophenol (DNP) prolongs the life span of mice, reduces traumatic brain damage, and inhibits the development of a number of neurodegenerative diseases. Unfortunately, DNP has a number of disadvantages that hinder its practical use. Uncoupling of oxidative phosphorylation by free fatty acids is a natural mechanism, the activation of which can be used in medicine. The third (after antioxidants and uncouplers), but so far little studied, method of reducing ROS is telomerase, which, under conditions of oxidative stress, is transported into the mitochondria and improves cell survival by reducing ROS production.

Senescent phenotype of trabecular meshwork cells displays biomarkers in primary open-angle glaucoma.

Glaucoma is a major cause of irreversible blindness, affecting more than 70 million individuals worldwide. Elevated intraocular pressure (IOP) is a major risk factor in the development of glaucoma and in the progression of glaucomatous damage. High IOP usually occurs as a result of an increase in aqueous humor outflow resistance in trabecular meshwork (TM). Primary open angle glaucoma (POAG) is characterized by quantifiable parameters including the IOP, the aqueous outflow facility, and geometric measurements of the optic disc and visual defects. Morphological and biochemical analyses of the TM of POAG patients revealed loss of cells, increased accumulation of extracellular matrix (ECM), changes in the cytoskeleton, cellular senescence and the process of subclinical inflammation. Various biochemical and molecular biology biomarkers of TM cells senescence are considered in the article. Oxidative stress is becoming an important factor more likely to be involved in the pathogenesis of POAG. Treatment of TM cells with oxidative stress induced POAG-typical changes like ECM accumulation, cell death, disarrangement of the cytoskeleton, advanced senescence and the release of inflammatory markers. Oxidative stress is able to induce characteristic glaucomatous TM changes and these oxidative stress-induced TM changes can be minimized by the use of antioxidants, such as carnosine-related analogues and IOP-lowering substances. There is evidence demonstrating that carnosine related analogues may have antioxidative capacities, can prevent cellular senescence and the attrition of telomeres during the action of oxidative stress. Prevention of oxidative stress exposure to the TM with N-acetylcarnosine ophthalmic prodrug of carnosine and oral formulation of non-hydrolized carnosine may help to reduce the progression of POAG. The previous work has demonstrated that carnosine is able to reach the TM directly via the transcorneal and systemic pathways of administration with N-acetylcarnosine ophthalmic prodrug and oral formulation of non-hydrolized carnosine. We suggest in this article that dual therapy with N-acetylcarnosine lubricant eye drops, oral formulation of non-hydrolized carnosine combined with anti-glaucoma adrenergic drug may become the first-line therapy in glaucoma due to their efficiency in reducing IOP, prevention and reversal of oxidative stress-induced damages in TM and the low rate of severe side effects during combined treatment.

A survey and analysis of the role of molecular chaperone proteins and imidazole-containing dipeptide-based compounds as molecular escorts into the skin during stress, injury, water structuring and other types of cutaneous pathophysiology.

Molecular chaperone, heat shock proteins (HSPs), stabilizes intracellular processes of cells under stress. Little is known about the role of molecular chaperone proteins in the skin pathology, rejuvenation and wound healing, or whether their expression is altered by environmental and physiological stress to the skin or systemic disease. The focus of this study was to examine the role of molecular chaperone proteins in the skin's local response to wounding, skin ageing and a range of skin diseases. Free radicals, one form of insult, induce or contribute to adverse effects on the skin, including erythema, oedema, wrinkling, photoaging, inflammation, autoimmune reactions, hypersensitivity, keratinization abnormalities, preneoplastic lesions and skin cancer. A unified view of the molecular and cellular pathogenesis of the skin age-related pathology conditions has led to the search for molecular and chemical chaperones that can slow, arrest or revert disease progression. Specific alpha-crystallin domains and pharmacological imidazole-containing dipeptide chaperone molecules are now emerging that link our biophysical insights with developed skin therapeutic techniques. In this article, we discuss the molecular nature of the stress signals, the mechanisms that underlie activation of the heat shock response, the role of molecular chaperone proteins as skin protective molecules, and strategies for pharmacologically active chaperone molecules and their imidazole-containing dipeptide inducers as regulators of the skin stress response. We discuss how impairment in protein hydration may cause ultrastructural, mechanical and biochemical changes in structural proteins in the aged skin. We have pioneered the molecular chaperone protein activated therapeutic or cosmetic platform to enable simultaneous analysis of water-binding and structuring characteristics for biology of skin ageing and skin disease-related pathways. This cutting-edge technology has improved the way that proteins hydrate in photoaged skin. The mechanisms of skin diseases, ageing, cellular, and signalling pathways mediated by targeting with molecular chaperone protein(s) in patented formulations with imidazole containing dipeptide (N-acetylcarnosine, carcinine, carnosine) are also discussed within this review.

Telomerase-dependent reactivation of DNA synthesis in macrophages implies alteration of telomeres.

In previous work we demonstrated that various types of cultured cells with a limited life span could not reactivate DNA synthesis in the nuclei of mouse peritoneal macrophages in heterokaryons. We now investigate the role of telomerase in the process of the macrophage nucleus reactivation in heterokaryons with immortal telomerase-positive 3T3 Swiss mouse fibroblasts and human fibroblasts with introduced hTERT gene. We report that introduction of the hTERT gene into human diploid fibroblasts results in emergence of telomerase activity in these cells and the ability to induce the reactivation of DNA synthesis in the macrophage nuclei in heterokaryons. Inhibition of telomerase activity in heterokaryons by reverse transcriptase inhibitors (azidothymidine and guanosine polyphosphonate analogues) and by a 2'-O-methyl-RNA oligonucleotide anti-sense to the template region of telomerase RNA, block reactivation of DNA synthesis in macrophage nuclei without inhibiting DNA synthesis in the nuclei of fibroblasts. Our results suggest alterations (shortening or damage) in the macrophage telomere structure. As far as we know, heterokaryons with macrophages are the first cellular model for rapid investigation of the effects of telomerase inhibitors.

Telomerase activity of cells during alterations of their proliferative states.

We showed that the telomerase activity (TAC) of human promyelocytic leukemic cells U-937 and HL-60 sharply decreased after induction of macrophagal differentiation. Dedifferentiation which occurred several days after removing the inductor was accompanied by the resumption of proliferation and increase of TAC. Telomerase activity significantly decreased also when U-937 cells ceased to proliferate in response to long-term inhibition of the telomerase function by azidothymidine. TAC was observed to decrease slowly for 6-8 days in the course of transition of mouse fibroblasts 3T3 Swiss to the quiescent state. TAC decreased both in serum-deprived cells and in slowly proliferating high-density inhibited cells. During the exit from quiescence and in dedifferentiation, the increase in TAC preceded the resumption of proliferation. In all the cases described the alterations of TAC correlated with alterations in the nonspecific polymerase activity which we had found earlier (D. N. Chernov, Y. E. Yegorov, and S. S. Akimov, DokL Biochemistry 349:55-58 (1996)). The problems of TAC regulation are discussed.

Blockade of telomerase function in various cells.

The reverse transcriptase inhibitors (RTI) azidothymidine and carbovir can block telomerase function in various cells, whereas dideoxycytidine does not exhibit such activity. RTI induce senescence in 3T3 Swiss, NIH 3T3 cell cultures and in the clones of immortal spontaneously transformed mouse fibroblasts. The RTI-induced senescence of L6 rat myoblasts in culture resembles the senescence of fibroblasts, but the resulting cells acquire sharp morphological peculiarities. The artificial senescence of fibroblasts and myoblasts resulted in both the appearance of corresponding senescent cells and a small portion of cells with the signs of another type of differentiation. The blockade of telomerase function by RTI in the human tumour cell lines U-937 and MeWo leads to the shortening of telomeres, but does not result in senescence. These cells may undergo crisis and after a while the proliferation resumes and resistant cells appear. RTI inhibit spontaneous reactivation of telomerase in the process of spontaneous transformation of mouse embryonic fibroblasts, which leads to the formation of telomerase-free clones. A fraction of these clones may overcome the senescence via the acquisition of telomerase activity. Cells with a very high level of telomerase activity become resistant to RTI. Thus, the blockade of telomerase function in different cells can induce senescence, partial differentiation or crisis. In human tumour cells it induces mainly crisis.

Endogenous beta-galactosidase activity in continuously nonproliferating cells.

Cytochemically detectable activity of endogenous beta-galactosidase was found at pH 6.0 in Swiss 3T3 cells after long-term incubation in low serum or in the presence of heparin concentrations known to reversibly inhibit cell proliferation. A high percentage of beta-galactosidase-positive cells were detected in U937 and HL60 cultures at the late stage of macrophage-like differentiation induced by TPA. Interestingly, a small number of beta-galactosidase-positive cells were found even in the growing Swiss 3T3 cultures. These positive cells expressed morphological features similar to those of senescent cells. Thus, the activity of beta-galactosidase at pH 6.0 cannot be considered an exclusive marker of senescent cells since it is expressed in other types of nonproliferating cells.

Blockade of telomerase function by nucleoside analogs.

Two types of spontaneously transformed cells appear in the culture of senescent mouse embryonic fibroblasts. The first type are cells with restricted proliferative potential (up to 30 population doublings); the other type are immortalized cells. Cells of the first type, unlike those of the second, have no telomerase activity and undergo two rounds of senescence. Spontaneous transformation of mouse embryonic fibroblasts in the presence of the reverse transcriptase inhibitors azidothymidine and carbovir led to the formation of telomerase-free clones. A fraction of these clones have the ability to overcome senescence via the acquisition of high telomerase activity. Cells with a very high level of telomerase activity become resistant to azidothymidine and carbovir. Azidothymidine-induced artificial senescence of rat myoblasts in culture resembles the senescence of fibroblasts, but the resulting cells acquire sharp morphological peculiarities. The blockade of telomerase function by azidothymidine in human U-937 and MeWo cells leads to the shortening of telomeres, but does not result in senescence. A hypothesis of the generation of the signal that induces senescence is proposed. This hypothesis suggests a change in DNA conformation during telomere shortening as a result of a change of loop structure of telomeric chromatin.

Reverse transcriptase inhibitors suppress telomerase function and induce senescence-like processes in cultured mouse fibroblasts.

Spontaneous transformation of mouse embryonic fibroblasts in the presence of the reverse transcriptase inhibitors azidothymidine and carbovir led to the formation of telomerase-free clones. After prolonged cultivation of fibroblasts in the presence of carbovir, resistant cells with a very high level of telomerase activity were obtained. Azidothymidine and carbovir, but not dideoxycytidine, induced senescence-like processes in cultures of immortal mouse fibroblasts. After long-term incubation, cell proliferation gradually decreased, their morphology becoming similar to that of the senescent ones. The process was reversible: after inhibitor removal, the cells, including the giant ones, entered mitoses. All these data suggest that reverse transcriptase inhibitors block telomerase function in mouse cells.

The comparison of DNA synthesis inducibility by high potassium treatment in various nonproliferating cells.

Previous studies have demonstrated that treatment of fibroblasts from confluent, density-inhibited cultures with 50 mM KCl solution led to the onset of DNA replication. In the present study we show that such treatment can induce aphidicolin-sensitive DNA replication in differentiated nondividing cells: dorsal root ganglia neurons and in vitro differentiated myotubes formed by L6 myoblasts. Murine peritoneal macrophages and macrophages/granulocytes derived from human promyelocytic leukemia cells HL60 are refractory to high potassium treatment. These results confirm the nonuniformity of the nonproliferative state of various differentiated cells.

The short-term increase in extracellular potassium concentration causes DNA replication onset in density-inhibited cells.

The high potassium concentration effect on the human diploid fibroblasts (HDF) and 3T3 cells was investigated. The incubation of confluent cultures of HDF or 3T3 Swiss cells in the medium with 50 mM K+ for 35 min induced, 12 h later, the onset of DNA replication in a significant proportion of culture cell population. The same treatment had no effect upon the sparce cell cultures. No stimulation of DNA replication was observed in the absence of serum in culture medium.

Resident macrophages specifically inhibit DNA synthesis in the nuclei of transformed cells in heterokaryons.

DNA synthesis in heterokaryons of mouse peritoneal macrophages and various proliferating cultured cells was analyzed. Macrophages did not inhibit replication in the nuclei of non-immortalized and spontaneously immortalized cells (rat fibroblasts and macrophages, mouse pre-macrophages, NIH3T3 cells). On the contrary, the percentage of DNA-synthesizing nuclei of malignant HeLa cells was drastically reduced in heterokaryons. The transformation of NIH3T3 cells with c-Ki-ras oncogene and that of rat chondrocytes with p53 oncogene made these cells sensitive to the replication-inhibiting activity of macrophages in heterokaryons. Our observation represents a kind of "intracellular" cytotoxic activity of macrophages directed against transformed cells.